Process for producing amorphous anisotropic melt-forming polymers having a high degree of stretchability and polymers produced by same

ABSTRACT

Process for producing highly stretchable, amorphous anisotropic melt-forming polymers consisting essentially of recurring units derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, an aromatic diacid, at least a portion of which comprises 2,6-naphthalene dicarboxylic acid, and an aromatic diol and/or hydroxyamine component, at least a portion of which is 4,4′-biphenol; which comprises incorporating into such polymers recurring units derived from resorcinol, wherein each of said recurring units is present in the polymer in specified amounts.

RELATED APPLICATIONS

The following copending applications, filed on even date herewith, allcontain related subject matter: U.S. application Ser. Nos.: 09/483,103,09/484,120 and 09/483,589. This amendment identifies the relatedco-pending applications by Serial number.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for producing highlystretchable amorphous anisotropic melt-forming polymers suitable for usein the production of a variety of shaped articles including films,fibers, and blow molded forms. This invention also relates to thepolymers produced from the subject process, as well as to shapedarticles made from such polymers.

2. Description of the Prior Art

Anisotropic melt-forming polymers, also known as liquid crystallinepolymers or “LCPs”, are well known in the art. Anisotropic melt-formingpolymers exhibit a parallel ordering of molecular chains in the meltphase and are also termed “thermotropic” liquid crystal polymers. Manyof these materials are wholly aromatic in nature.

Thermotropic polymers include aromatic copolyesters having recurringunits derived from p-hydroxybenzoic acid, at least one aromatic diol andat least one aromatic dicarboxylic acid as well as wholly aromaticcopolyesteramides having recurring units derived from p-hydroxybenzoicacid, at least one aromatic diol, at least one aromatic diacid, andaminophenol. Without the inclusion of recurring units that disrupt thecrystalline structure, such polymers tend to have very high meltingpoints, for example, 360° C. and above, making them difficult to meltfabricate. Incorporation of recurring units that provide non-parallel or“kinky” linkages is a common means of lowering melting point. Thesekinky linkages include “meta”or 1,3-aromatic ring structures.

Common materials from which meta linkages are derived includem-hydroxybenzoic acid, isophthalic acid, resorcinol, and m-aminophenol.U.S. Pat. Nos. 4,563,508; 5,037,939; and 5,066,767 disclose polymerscontaining recurring units derived from p-hydroxybenzoic acid,terephthalic acid, isophthalic acid, hydroquinone and 4,4′-biphenol;U.S. Pat. No. 4,912,193 discloses polymers having recurring unitsderived from p-hydroxybenzoic acid, 4,4′-biphenol, terephthalic acid andisophthalic acid; U.S. Pat. No. 4,966,956 discloses polymers havingrecurring units derived from p-hydroxybenzoic acid, terepthalic acid,isophthalic acid, 4,4′-biphenol and aminophenol; U.S. Pat. No. 5,663,276discloses polymers having recurring units derived from p-hydroxybenzoicacid, terephthalic acid, 4,4′-biphenol, isophthalic acid, hydroquinoneand 4,4′-biphenyldicarboxylic acid; U.S. Pat. No. 5,089,594 disclosespolymers having recurring units derived from p-hydroxybenzoic acid,terephthalic acid, isophthalic acid, 4,4′-biphenol, and an aromaticdiol, for example, hydroquinone; U.S. Pat. No. 4,722,993 disclosespolymers having recurring units derived from m-aminophenol,p-hydroxybenzoic acid, terephthalic and/or isophthalic acid, one or moreof hydroquinone, 4,4′-biphenol or resorcinol and, if desired,m-hydroxybenzoic acid; U.S. Pat. No. 5,399,656 discloses polymers havingrecurring units derived from p-hydroxybenzoic acid, terephthalic acid,resorcinol and an aromatic diol, for example, 4,4′-biphenol; U.S. Pat.No. 5,025,082, discloses polymers having recurring units derived fromp-hydroxybenzoic acid, terephthalic acid, 4,4′-biphenol, 2,6-naphthalenedicarboxylic acid, and at least one aromatic diol selected fromhydroquinone, methylhydroquinone, trirnethylhydroquinone, resorcinol andtetramethylbiphenol; and U.S. Pat. No. 5,798,432 discloses polymershaving requiring units derived from p-hydroxy benzoic acid,2,6-naphthalene dicarboxylic acid, terephthalic acid, isophthalic acid,hydroquinone, p-aminophenol and 4,4′-biphenol.

The presence of meta linkages notwithstanding, aromatic polymers derivedfrom p-hydroxybenzoic acid, at least one aromatic dicarboxylic acid andat least one aromatic diol and/or aminophenol tend to have highlyordered crystalline structures and, although drawable in the melt,generally lack the ability to be stretched to a significant degree attemperatures below the molten state.

Another class of thermotropic polymers have recurring units derived fromp-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, at least one aromaticdiacid and at least one aromatic diol. The incorporation of metalinkages into such polymers is described, for example, in the following:U.S. Pat. No. 4,522,974 disclosing polymers having recurring unitsderived from p-hydroxy benzoic acid, 6-hydroxy-2-naphthoic acid,hydroquinone and isophthalic and/or terephthalic acid; U.S. Pat. No.4,920,197 disclosing polymers having recurring units derived fromp-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, terephthalic acid,isophthalic acid and resorcinol; U.S. Pat. No. 4,937,310 disclosingpolymers having recurring units derived from p-hydroxybenzoic acid,6-hydroxy-2-naphthoic acid, terephthalic acid, isophthalic acid andresorcinol; U.S. Pat. No. 4,918,154 disclosing polymers having recurringunits derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid,terephthalic and/or isophthalic acid, resorcinol and hydroquinone; andU.S. Pat. No. 4,983,713 disclosing polymers having recurring unitsderived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid,terephthalic acid, 4,4′-biphenol, and isophthalic acid. The polymers setforth in the examples of these patents tend to have ordered crystallinestructures and are not considered to be highly stretchable materials.

More recent patents disclose liquid crystalline polymers that includeamorphous materials. Example 5 of U.S. Pat. No. 5,525,700 is directed towhat appears to be an amorphous polymer having recurring units derivedfrom p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, hydroquinone,terephthalic acid, 4,4′-biphenol and 2,6-naphthalene dicarboxylic acid.Crystalline polymers derived from the same recurring units are alsodisclosed. In fact, of the numerous polymers exemplified by this patent,all but Example 5 are crystalline materials. Example 5 is not believedto be a highly stretchable polymer.

U.S. Pat. No. 5,656,714 discloses amorphous and what are termed“semi-crystalline” polymers having recurring units derived fromp-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, terephthalic acid,4,4′-biphenol, and resorcinol. Fibers made from the amorphous polymersof Examples I and IX were respectively reported to be drawn to 73 and 30times their as-spun length. Apart from Examples I and IX, no additionaldata regarding the stretchability of the exemplified polymers isprovided. The polymers exemplified by U.S. Pat. No. 5,656,714 vary interms of their degree of crystallinity; some, but not all, of thesepolymers are highly stretchable.

LCPs that are stretchable at lower temperatures have a diverse range ofend-use applications. Amorphous LCPs having a Tg (i.e., onset of theglass transition temperature as measured by differential scanningcalorimetry or “DSC”) of 150° C. or less that are highly stretchable attemperatures above Tg, but below the temperature at which the LCP is inthe molten state, are of particular interest in the production ofarticles that are stretched, drawn or otherwise processed at lowertemperatures. Liquid crystalline polymers that are stretchable attemperatures below the processing temperatures of conventionalfilm-forming polymers such as, for example, polyolefins or polyalkyleneterephthalates, for example, PBT or PET, may be particularly desirablefor use in the production of multilayer articles such as films,laminates, blow-molded containers, and the like. In these multi-layerapplications, the barrier, mechanical and/or optical properties ofliquid crystalline polymers may provide advantages that are typicallynot obtained from conventional thermoplastics. EP 0 928 683 A2,published Jul. 14, 1999, discloses a variety of multi-layer laminates,including laminates formed from wholly aromatic, liquid crystallinepolymers of the type disclosed in U.S. Pat. No. 5,656,714.

A process for producing highly stretchable amorphous LCPs and the LCPsso produced are desired.

SUMMARY OF THE INVENTION

It now been found that in order to produce highly stretchable amorphousanisotropic polymers, it is necessary to provide the polymer withspecific recurring units in narrowly defined amounts. In one embodiment,the present invention is directed to a process for forming highlystretchable, amorphous anisotropic melt-forming polymers which comprisesincorporating recurring unit V of the formula:

into a polymer comprising recurring units I, II, III, and IV, whereinrecurring unit I is:

recurring unit II is:

recurring unit III is:

wherein Ar¹ is selected from the group consisting of:

and mixtures thereof;

and recurring unit IV is:

—O—Ar²—X—  IV

wherein Ar² is selected from the group consisting of:

and mixtures thereof, and X is independently selected from the groupconsisting of O and NR² wherein R² is independently selected from thegroup consisting of hydrogen and C₁ to C₆ alkyl;

to provide a polymer that consists essentially of from about 15 to about60 mole percent of recurring unit I, from about 15 to about 60 molepercent of recurring unit II, from about 5 to about 20 mole percent ofrecurring unit III, from about 5 to about 20 mole percent of recurringunit IV, and from about 7 to about 15 mole percent of recurring unit V,wherein:

(a) recurring units I and II combined are present in the polymer in anamount of from about 50 to about 75 mole percent,

(b) the polymer contains at least about 5 mole percent of recurringunits of the formula:

(c) at least a portion of recurring unit III is:

In a further embodiments this invention is directed to anisotropicmelt-forming polymers produced in accordance with the process describedin the immediately preceding paragraph as well as to stretched articlesformed from such polymers.

DETAILED DESCRIPTION OF THE INVENTION

The process of this invention produces highly stretchable amorphouspolymers. The polymers are considered to be amorphous in that they lacka well defined melting point or T_(m) (i.e., a solid to nematicendothermic peak as measured by differential scanning calorimetry).Despite the absence of a classic melting point, the subject polymerspossess a solid to nematic fluid transition temperature that definestheir melt processability. Polymers produced in accordance with thisinvention are melt processable at temperatures below about 270° C.Additionally, such polymers have T_(g) values of about 150° C. or less.Preferably, the polymers have T_(g) values of about 130° C. or less,most preferably about 120° C. or less. For co-extrusion applicationswith polyolefins, polymers that are melt processable at temperatures ator below 220° C. are of particular interest.

As noted above, the thermal properties of liquid crystalline polymersvary with composition. While almost all liquid crystalline polymers arestretchable in the melt, relatively few are stretchable at temperaturesbelow which they are molten. The extent to which a polymer can bestretched or drawn depends upon the temperature at which stretchingoccurs as well as the form and size of the material that is beingstretched. LCPs of the subject invention exhibit a percentage of breakstrain at break point (herein also referred to as the polymer's degreeof stretchability) of at least about 100% when spun into tapes that aretested in accordance with the procedure set forth in the Examples below.

Anisotropic melt-phase forming polymers formed by the present inventionconsist essentially of at least five different recurring units. Unit Iof the subject polymers, termed a para-oxybenzoyl unit, possesses thestructural formula:

While not specifically illustrated in the structural formula, at leastsome of the hydrogen atoms present on the aromatic ring of unit I may besubstituted. Included among the representative precursors from whichrecurring unit I may be derived are: 4-hydroxybenzoic acid;3-chloro-4-hydroxybenzoic acid; 3-methyl-4-hydroxybenzoic acid;3-methoxy-4-hydroxybenzoic acid 3-phenyl-4-hydroxybenzoic acid;3,5-dichloro-4-hydroxybenzoic acid; 3,5-dimethyl-4-hydroxybenzoic acid;3,5-dimethoxy-4-hydroxybenzoic acid; and the like. In a preferredembodiment, no ring substitution is present on recurring unit I.Recurring unit I is present in the polymers of the subject invention inan amount of from about 15 to about 60 mole percent, preferably fromabout 20 to about 40 mole percent.

Recurring unit II of the subject polymers, termed a 6-oxy-2-naphthoylunit, possesses the structural formula:

As in the case of recurring unit I, at least some of the hydrogen atomspresent on the aromatic ring structure of recurring unit II may besubstituted. Exemplary of such substituents are alkyl groups of 1 to 4carbon atoms, alkoxy groups of 1 to 4 carbon atoms, phenyl, halogen(e.g., Cl, Br, and I), and mixtures thereof. Representative of theprecursors from which recurring unit II may be derived are aromatichydroxy-naphthoic acids which include: 6-hydroxy-2-naphthoic acid;6-hydroxy-5-chloro-2-naphthoic acid; 6-hydroxy-5-methyl-2-naphthoicacid; 6-hydroxy-5-methoxy-2-naphthoic acid;6-hydroxy-5-phenyl-2-naphthoic acid; 6-hydroxy-7-chloro-2-naphthoicacid; 6-hydroxy-5,7-dichloro-2-naphthoic acid, and the like. In apreferred embodiment no ring substitution is present on recurring unitII. Recurring unit II is present in the subject polymers in an amount offrom about 15 to about 60 mole percent, preferably from about 20 toabout 40 mole percent. Combined, recurring units I and II comprise fromabout 50 to about 75 mole percent, preferably from about 60 to about 70mole percent of the subject polymers.

Recurring unit III of the subject polymers possesses the structuralformula:

wherein Ar¹ is a divalent radical selected from the group consisting of:

and mixtures thereof, wherein at least a portion of recurring unit IIIis

The amount of recurring III that is made up of unit IIIa is variable. Inone embodiment recurring unit III contains at least about 50 molepercent of unit IIIa; in other embodiments recurring unit III contains aminimum of 30 mole percent or less of unit IIIa. Although notspecifically shown in the formulas given, the aromatic ring structure ofrecurring unit III may be substituted in a manner similar to thatdescribed for recurring unit I. Preferably no ring substitution ispresent on recurring unit III. Recurring unit III is derived, forexample, from precursors such as 2,6-naphthalene dicarboxylic acid aloneor in combination with terephthalic acid and/or4,4′-biphenyldicarboxylic acid. Recurring unit III is present in thepolymers of the subject invention in an amount of from about 5 to about20 mole percent, preferably from about 10 to about 15 mole percent. Inone embodiment of interest, recurring unit III consists of:

In another embodiment interest, recurring unit III consists of a mixtureof units:

Recurring unit IV of the subject polymers, possesses the formula:

—O—Ar²—X—

wherein Ar² and X are as previously defined. Although not specificallyillustrated in the structural formula given, the aromatic ring structureof recurring unit IV may be substituted in a manner similar to thatdescribed for recurring unit I. Representative of the precursors fromwhich recurring unit IV may be derived are aromatic diols such as, forexample, 4,4′-biphenol, hydroquinone, 2,6-naphthalene diol,p-aminophenol, and the like. Preferably, no ring substitution is presenton recurring unit IV. Recurring unit IV is present in the polymers ofthe subject invention in an amount of from about 5 to about 20 molepercent, preferably from about 10 to about 15 mole percent. In thepractice of this invention, the subject polymers contain at least about5 mole percent of recurring units of the formula:

In one embodiment of particular interest recurring unit IV consists ofunits of the formula:

In another embodiment of interest, recurring unit IV consists of amixture of the following units:

Recurring unit V of the subject polymers has the formula:

Although not specifically illustrated in the structural formula given,the aromatic ring structure of recurring unit V may be substituted in amanner similar to that described for recurring unit I. Preferably, noring substitution is present on recurring unit V. In the practice ofthis invention, recurring unit V is present in the subject polymer in anamount of from about 7 to about 15 mole percent, preferably from about10 to about 15 mole percent. Resorcinol is a preferred precursor fromwhich recurring unit V is derived.

Minor amounts of other units that provide ester or ester-amide linkagesmay be present, provided, that such units do not obviate the propertiesdesired by this invention. It will be apparent to those skilled in theart that the total amount of dioxy and oxy-amino units present in thesubject polymers will be substantially equal to the total amount ofdicarboxy units. In general, the various recurring units will be presentin the resultant polymers in a random configuration. Preferably thepolymers are wholly aromatic materials.

The polymers formed by the process of this invention commonly exhibit aweight average molecular weight of from about 10,000 to about 80,000.The molecular weight of preference will depend, in part, on the intendedend-use application. For example, in fiber and film applications, weightaverage molecular weights of from about 20,000 to about 40,000 arecommonly of interest. The polymers typically exhibit an inherentviscosity (I.V.), measured at 25° C. as a 0.1% by weight solution ofpolymer in a mixture of equal volumes of pentafluorophenol andhexafluorisopropanol, of at least about 1.0 dl/g, with polymers havinginherent viscosities of from about 3.0 dl/g to about 7.0 dl/g being ofparticular interest.

Characteristic of the subject polymers is the formation of ananisotropic melt phase. Thus, in the melt there is a tendency for thepolymer chains to orient in the shear direction. Such thermotropicproperties are manifest at a temperature which is amenable for meltprocessing to form shaped articles. Anisotropy in the melt may beconfirmed by conventional polarized light microscopy techniques.

The polymers of this invention are typically prepared by apolymerization reaction that proceeds through the acetate form of thehydroxycarboxylic acid, diol and, when present, hydroxyamine reactants.Thus, it is possible to employ as starting materials reactants havingpre-acetylated hydroxyl groups and amino groups, heat the reaction mixto polycondensation temperature and maintain reaction until a desiredpolymer viscosity is reached. Alternatively, it is possible to acetylatein situ, in which case the aromatic hydroxycarboxylic acid, aromaticdiol and, when present, hydroxyamine are reacted with acetic anhydride,acetic acid by-product is removed, the esterified reactants togetherwith the aromatic diacid are heated to polycondensation temperature, andreaction is maintained until a desired polymer viscosity is reached. Thearomatic diacid reactant may, but need not, be present during theacetylation reaction. If the acetylation and polycondensation reactionsare conducted in a single reactor, it is common to charge the reactorwith the reactant materials in a single step.

Using separate acetylation and polymerization reactors, it may bedesirable to introduce the diacid component to the polymerizationreactor as opposed to the acetylation reactor. The acetylation andpolycondensation reactions are typically conducted in the presence ofsuitable catalysts. Such catalysts are well known in the art andinclude, for example, alkali and alkaline earth metal salts ofcarboxylic acids, such as, for example, potassium acetate, sodiumacetate, magnesium acetate, and the like. Such catalysts are typicallyused in amounts of from about 50 to about about 500 parts per millionbased on the total weight of the recurring unit precursors.

Acetylation is generally initiated at temperatures of about 90° C. Inthe initial stage of the acetylation reflux is desirably employed tomaintain vapor phase temperature below the point at which acetic acidbyproduct and anhydride begin to distill. Temperatures during theinitial stage of acetylation typically range from between 90° to 150°C., preferably about 100° to about 130° C. In order to complete theacetylation, the reaction mixture is then heated to final melttemperature of about 150° to about 220° C., preferably about 150° toabout 200° C., with temperatures of 180° to 200° C. being of particularinterest. At this point, if reflux is used, the vapor phase temperatureshould exceed the boiling point of acetic acid but remain low enough toretain residual acetic anhydride.

To ensure substantially complete reaction, it may be desirable toutilize an excess amount of acetic anhydride in conducting theacetylation. The amount of excess anhydride utilized will vary dependingupon the particular acetylation conditions employed, including thepresence or absence of reflux. The use of an excess of from about 1 toabout 10 mole percent of acetic anhydride, based on the total moles ofreactant hydroxyl groups present is not uncommon.

To obtain both complete acetylation and maintenance of stoichiometricbalance, anhydride loss should be minimized. Acetic acid vaporizes attemperatures of about 118° C. At higher temperatures, i.e., about 140°C. acetic anhydride also begins to vaporize. Providing the reactor witha means of controlling vapor phase reflux is desirable. Maintainingvapor phase reflux temperature at about 120° to about 130° C. isparticularly desirable.

Polycondensation of the acetylated starting materials generally beginsto take place at a temperature within a range of from about 210° toabout 260° C. As acetic acid is also a byproduct of the polymerizationreaction, it is desirable to employ controlled vapor phase reflux whenconducting the polycondensation reaction. In the absence of controlledvapor phase reflux, acetic anhydride, acetoxybenzoic acid and othervolatile materials are vaporized as the polymerization temperature isincreased. Depending on the particular polymer synthesized, it ispreferable to maintain vapor phase reflux temperatures of about 120° toabout 130° C. during the polymerization reaction.

As the final polymerization temperature is approached, volatilebyproducts of the reaction having boiling points above that of aceticacid and acetic anhydride should be removed. Accordingly at reactortemperatures of about 250° to about 300° C., vapor phase reflux, ifused, is generally adjusted to allow higher vapor phase temperatures oris discontinued. The polymerization is generally allowed to proceeduntil a desired polymer viscosity is reached. To build molecular weightin the melt, the polymerization reaction is generally conducted undervacuum, the application of which facilitates the removal of volatilesformed during the final stage of the polycondensation.

Following polymerization, the molten polymer is discharged from thereactor, typically through an extrusion orifice fitted with a die ofdesired configuration; cooled; and collected. Commonly, the melt isdischarged through a perforated die to form strands which are taken upin a water bath, pelletized and dried.

In an embodiment of particular interest this invention is directed tohighly stretchable, amorphous anisotropic melt-forming polymersconsisting essentially of recurring units I, II, III, IV and V, whereinrecurring unit I is

recurring unit II is:

recurring unit III is:

recurring unit IV is:

—O—Ar²—O—

wherein Ar² is selected from the group consisting of:

and mixtures thereof; and

recurring unit V is:

wherein said polymer contains from about 20 to about 40 mole percent ofrecurring unit I, from about 20 to about 40 mole percent of recurringunit II, from about 10 to about 15 mole percent of recurring unit III,from about 10 to about 15 mole percent of recurring unit IV, and fromabout 10 to about 15 mole percent of recurring unit V and wherein:

(a) recurring units I and II combined are present in the polymer in anamount of from about 60 to about 70 mole percent and

(b) the polymer contains at least about 5 mole percent of recurringunits of the formula:

In another embodiment of particular interest this invention is directedto highly stretchable, amorphous anisotropic melt-forming polymersconsisting essentially of recurring units I, II, III, IV and V, whereinrecurring unit I is

recurring unit II is:

recurring unit III consists of a mixture of:

recurring unit IV is:

and recurring unit V is:

wherein said polymer contains from about 30 to about 35 mole percent ofrecurring unit I, from about 30 to about 35 mole percent of recurringunit II, from about 10 to about 15 mole percent of recurring unit III,from about 10 to about 15 mole percent of recurring unit IV, and fromabout 10 to about 15 mole percent of recurring unit V.

Although the polymers produced by the process of this invention areparticularly well suited for extrusion and co-extrusion applicationssuch as the production of fiber, film, sheet, blow molded articles andthe like, they may also be used in the production of injection moldedparts. If desired, compositions containing the subject polymers maycontain one or more additional optional components such as for example,colorants, lubricants, processing aids, stabilizers, fillers,reinforcing agents, and the like. Fillers and reinforcing agents are nottypically present in compositions used in fiber and film applications.

EXAMPLES

The following examples are presented to further illustrate thisinvention. The examples are not, however, intended to limit theinvention in any way.

Example 1 and Comparative Examples C₁ and C₂

To a 3-necked cylindrically shaped flask equipped with a stainless steel“C”-shaped agitator, gas inlet tube, thermocouple, distilling trap andVigreux column attached to a condenser and receiver were added:

331.2 grams p-hydroxybenzoic acid

225.6 grams 6-hydroxy-2-naphthoic acid

99.6 grams of terephthalic acid

111.6 grams of 4,4′-biphenol

129.6 grams of 2,6-naphthalene dicarboxylic acid

66.0 grams of resorcinol

632.9 grams of acetic anhydride

0.12 grams of potassium acetate (60 ppm)

The flask was purged of oxygen by evacuation and flushing with driednitrogen and immersed into an electrically heated fluidized sand bath.The contents of the flask were heated to ˜150° C. while stirring at 75rpm to acetylate hydroxyl groups. Temperature was raised from 150° to220° C. over a period of 70 minutes to distill by-product acetic acid.Polymerization commenced at 220° C. and batch temperature was raised to340° C. over a period of 130 minutes. During this time acetic acid thatevolved was removed by distillation. After a 30 minute hold time at 340°C., vacuum was applied and the pressure gradually reduced to ˜5 mm Hgover a period of 20 minutes. The vacuum was maintained until the torquerequired to maintain agitator speed reached the target value necessaryto give the desired melt viscosity. At the target torque the vacuum wasdiscontinued and the flask brought to atmospheric pressure with drynitrogen.

This process produced a polymer having an inherent viscosity (I.V.) of3.0 dl/g, as measured at 25° C. as a 0.1% by weight solution of polymerin a mixture of equal volumes of pentafluorophenol andhexafluoroisopropanol. The melt viscosity (M.V.) of the polymer was˜1500 poise, at a shear rate of 1000 sec⁻¹, measured at 270° C. in acapillary rheometer using an orifice 1 mm in diameter and 20 mm long.DSC (20° C./min. heating rate) indicated that the polymer had a Tg of110° C.

Additional polymers were made and tested following a similar procedure.Table 1 lists the various Examples and Comparative Examples togetherwith the mole percentages of the reactant monomers employed.Abbreviations are as follows:

“p-HBA” means p-hydroxybenzoic acid;

“HNA” means 6-hydroxy-2-naphthoic acid;

“TA” means terephthalic acid;

“NDA” means 2,6-naphthalene dicarboxylic acid;

“BP” means 4,4′-biphenol; and

“R” means resorcinol.

All polymerizations were conducted in the presence of 60 ppm potassiumacetate using sufficient acetic anhydride to completely acetylate thehydroxyl groups present.

Hot stage microscopy with polarized light confirmed that all of thepolymers were optically anisotropic. The polymers contained molarquantities of recurring units that corresponded to the molar charge ofthe reactant monomers. I.V., M.V., and T_(g) data for the polymers(measured as described above) are reported in Table 2. Excluding thosepolymers for which a T_(m) is reported, the polymers were amorphous.

TABLE 1 REACTANT MONOMERS (Mole %) Example p-HBA HNA TA NDA BP R 1 40 2010 10 10 10 C₁ 30 30 20 — 20 — C₂ 30 30 10 10 20 —

The polymers of Example 1 and Comparative Example C₁ were melt spun intotapes using a Micromelt™ apparatus. The apparatus was equipped with a0.127 mm by 6.35 mm die. Melt temperatures varied between 270-280° C.depending upon the melt characteristics of the sample. Throughput rateswere 0.45 cc/min; take-up roller speeds were 2 rpm; pack pressuresranged from about 110 kg/cm² to about 290 kg/cm², depending upon the Tg(or T_(m)) of the polymer. The resulting tapes had an approximatethickness of 0.05 mm and a width of about 6 mm.

Five test specimens, each 12.7 cm in length were cut from each tape. Thethickness of the specimens was measured to the nearest 0.0025 mm and thewidth to the nearest 0.25 mm. Each specimen was placed in a preheatedInstron oven, allowed 6 minutes to come to temperature and then testedon a Instron type universal tester (equipped with a thermal chamber),set to a test temperature of 150° C. The gauge length was set at 25 mmand the crosshead speed was set at 50.8 mm/min. The % break strain wascalculated at the break point. The % break strain is reported in Table 2as the average of the data for the five specimens tested. Standarddeviations are also provided.

TABLE 2 TESTING DATA BREAK STRAIN, % TEST I.V. M.V. Avg./Std. TEMP. TgEXAMPLE (dl/g) (poise) Dev. (° C.) (° C.) 1 3.0 1511 230/40  150 115 C₁9.5 2592 2.3/0.2 150 T_(m) of 250° C. C₂ —  823 — — T_(m) of 222° C.

What is claimed is:
 1. A process for forming highly stretchable,amorphous anisotropic melt-forming polymers which comprisesincorporating recurring unit V of the formula:

into a polymer comprising recurring units I, II, III, and IV, whereinrecurring unit I is:

recurring unit II is:

recurring unit III is:

wherein Ar¹ is selected from the group consisting of:

and mixtures thereof; and recurring unit IV is: —O—Ar²—X—  IV whereinAr² is selected from the group consisting of:

and mixtures thereof, and X is independently selected from the groupconsisting of O and NR² wherein R² is independently selected from thegroup consisting of hydrogen and C₁ to C₆ alkyl; to provide a polymerthat consists essentially of from about 15 to about 60 mole percent ofrecurring unit I, from about 15 to about 60 mole percent of recurringunit II, from about 5 to about 20 mole percent of recurring unit III,from about 5 to about 20 mole percent of recurring unit IV, and fromabout 7 to about 15 mole percent of recurring unit V wherein: (a)recurring units I and II combined are present in the polymer in anamount of from about 50 to about 75 mole percent, and (b) the polymercontains at least about 5 mole percent of recurring units of theformula:

(c) at least a portion of recurring unit III is:


2. A process as described in claim 1 wherein recurring unit III is:


3. A process as described in claim 1 wherein recurring unit III consistsof mixture of the following:


4. A process as described in claim 1 wherein recurring unit I is presentin the polymer in an amount of from about 30 to about 35 mole percent,recurring unit II is present in the polymer in an amount of from about30 to about 35 mole percent, recurring unit III is present in thepolymer in an amount of from about 10 to about 15 mole percent,recurring unit IV is present in the polymer in an amount of from about10 to about 15 mole percent, and recurring unit V is present in thepolymer in an amount of from about 10 to about 15 mole percent.
 5. Aprocess as described in claim 2 wherein recurring unit I is present inthe polymer in an amount of from about 30 to about 35 mole percent,recurring unit II is present in the polymer in an amount of from about30 to about 35 mole percent, recurring unit III is present in thepolymer in an amount of from about 10 to about 15 mole percent,recurring unit IV is present in the polymer in an amount of from about10 to about 15 mole percent, and recurring unit V is present in thepolymer in an amount of from about 10 to about 15 mole percent.
 6. Aprocess as described in claim 3 wherein recurring unit I is present inthe polymer in an amount of from about 30 to about 35 mole percent,recurring unit II is present in the polymer in an amount of from about30 to about 35 mole percent, recurring unit III is present in thepolymer in an amount of from about 10 to about 15 mole percent,recurring unit IV is present in the polymer in an amount of from about10 to about 15 mole percent, and recurring unit V is present in thepolymer in an amount of from about 10 to about 15 mole percent.
 7. Aprocess as described in claim 5 wherein recurring unit IV is


8. A process as described in claim 6 wherein recurring unit IV is


9. A highly stretchable, amorphous anisotropic melt-forming polymersconsisting essentially of recurring units I, II, III, IV and V whereinrecurring unit I is

recurring unit II is:

recurring unit III is:

wherein is Ar¹ is selected from the group consisting of:

and mixtures thereof; recurring unit IV is: —O—Ar²—X—  IV wherein Ar² isselected from the group consisting of:

and mixtures thereof, and X is independently selected from the groupconsisting of O or NR² wherein R² is independently selected from thegroup consisting of hydrogen and a C₁ to C₆ alkyl; and recurring unit Vis:

wherein recurring unit I is present in the polymer in an amount of fromabout 15 to about 60 mole percent, recurring unit II is present in thepolymer in an amount of from about 15 to about 60 mole percent,recurring unit III is present in the polymer in an amount of from about5 to about 20 mole percent, recurring unit IV is present in the polymerin an amount of from about 5 to about 20 mole percent, and recurringunit V is present in the polymer in an amount of from about 7 to about15 mole percent, wherein; (a) recurring units I and II combined arepresent in the polymer in an amount of from about 50 to about 75 molepercent and (b) the polymer contains at least about 5 mole percent ofrecurring units of the formula:

(c) at least a portion of recurring unit III is:


10. A polymer as described in claim 9 wherein recurring unit III is:


11. A polymer as described in claim 9 wherein recurring unit IIIconsists of a mixture of:


12. A polymer as described in claim 9 wherein recurring unit I ispresent in the polymer in an amount of from about 30 to about 35 molepercent, recurring unit II is present in the polymer in an amount offrom about 30 to about 35 mole percent, recurring unit III is present inthe polymer in an amount of from about 10 to about 15 mole percent,recurring unit IV is present in the polymer in an amount of from about10 to about 15 mole percent, and recurring unit V is present in thepolymer in an amount of from about 10 to about 15 mole percent.
 13. Apolymer as described in claim 10 wherein recurring unit I is present inthe polymer in an amount of from about 30 to about 35 mole percent,recurring unit II is present in the polymer in an amount of from about30 to about 35 mole percent, recurring unit III is present in thepolymer in an amount of from about 10 to about 15 mole percent,recurring unit IV is present in the polymer in an amount of from about10 to about 15 mole percent, and recurring unit V is present in thepolymer in an amount of from about 10 to about 15 mole percent.
 14. Apolymer as described in claim 11 wherein recurring unit I is present inthe polymer in an amount of from about 30 to about 35 mole percent,recurring unit II is present in the polymer in an amount of from about30 to about 35 mole percent, recurring unit III is present in thepolymer in an amount of from about 10 to about 15 mole percent,recurring unit IV is present in the polymer in an amount of from about10 to about 15 mole percent, and recurring unit V is present in thepolymer in an amount of from about 10 to about 15 mole percent.
 15. Apolymer as described in claim 13 wherein recurring unit IV is


16. A polymer as described in claim 14 wherein recurring unit IV is


17. A highly stretchable, amorphous anisotropic melt-forming polymerthat consists essentially of recurring units I, II, III, IV and V,wherein recurring unit I is

recurring unit II is:

recurring unit III is:

recurring unit IV is: —O—Ar²—O— wherein Ar² is selected from the groupconsisting of:

and mixtures thereof; and recurring unit V is:

wherein said polymer contains from about 20 to about 40 mole percent ofrecurring unit I, from about 20 to about 40 mole percent of recurringunit II, from about 10 to about 15 mole percent of recurring unit III,from about 10 to about 15 mole percent of recurring unit IV, and fromabout 10 to about 15 mole percent of recurring unit V and wherein: (a)recurring units I and II combined are present in the polymer in anamount of from about 60 to about 70 mole percent and (b) the polymercontains at least about 5 mole percent of recurring units of theformula:


18. A highly stretchable, amorphous anisotropic melt-forming polymersconsisting essentially of recurring units I, II, III, IV and V, whereinrecurring unit I is

recurring unit II is:

recurring unit III consists of a mixture of:

recurring unit IV is:

and recurring unit V is:

wherein said polymer contains from about 30 to about 35 mole percent ofrecurring unit I, from about 30 to about 35 mole percent of recurringunit II, from about 10 to about 15 mole percent of recurring unit III,from about 10 to about 15 mole percent of recurring unit IV, and fromabout 10 to about 15 mole percent of recurring unit V.
 19. A shapedarticle produced from the polymer of claim
 9. 20. A shaped articleproduced from the polymer of claim
 17. 21. A shaped article producedfrom the polymer of claim
 18. 22. A shaped article as described by claim19 which is a multilayer structure in which said amorphous anisotropicmelt-forming polymer is present as a barrier layer.
 23. A shaped articleas described by claim 20 which is a multilayer structure in which saidamorphous anisotropic melt-forming polymer is present as a barrierlayer.
 24. A shaped article as described by claim 21 which is amultilayer structure in which said amorphous anisotropic melt-formingpolymer is present as a barrier layer.
 25. A film formed from thepolymer of claim
 9. 26. A film formed from the polymer of claim
 17. 27.A film formed from the polymer of claim 18.